Fix for #1784

app/Http/Requests/AccountFormRequest.php

@@ -24,6 +24,7 @@ namespace FireflyIII\Http\Requests;
 
 use FireflyIII\Models\Account;
 use FireflyIII\Rules\UniqueIban;
+use FireflyIII\Rules\ZeroOrMore;
 
 /**
  * Class AccountFormRequest.
@@ -116,7 +117,7 @@ class AccountFormRequest extends Request
         ];
 
         if ('liabilities' === $this->get('what')) {
-            $rules['openingBalance']     = 'numeric|required|more:0';
+            $rules['openingBalance']     = ['numeric', 'required', new ZeroOrMore];
             $rules['openingBalanceDate'] = 'date|required';
         }
 

app/Rules/ZeroOrMore.php

@@ -0,0 +1,45 @@
+<?php
+
+namespace FireflyIII\Rules;
+
+use Illuminate\Contracts\Validation\Rule;
+
+/**
+ *
+ * Class ZeroOrMore
+ */
+class ZeroOrMore implements Rule
+{
+
+    /**
+     * Get the validation error message.
+     *
+     * @return string
+     */
+    public function message(): string
+    {
+        return trans('validation.zero_or_more');
+    }
+
+    /**
+     * Determine if the validation rule passes.
+     *
+     * @param  string $attribute
+     * @param  mixed  $value
+     *
+     * @return bool
+     */
+    public function passes($attribute, $value): bool
+    {
+        $value = (string)$value;
+        if ('' === $value) {
+            return true;
+        }
+        $res = bccomp('0', $value);
+        if ($res > 0) {
+            return false;
+        }
+
+        return true;
+    }
+}

resources/lang/en_US/validation.php

@@ -24,6 +24,7 @@ declare(strict_types=1);
 
 return [
     'iban'                           => 'This is not a valid IBAN.',
+    'zero_or_more'                   => 'The value cannot be negative.',
     'source_equals_destination'      => 'The source account equals the destination account.',
     'unique_account_number_for_user' => 'It looks like this account number is already in use.',
     'unique_iban_for_user'           => 'It looks like this IBAN is already in use.',